Thermal Stability Of Nylon Research Articles

Enhancing tribo-mechanical properties and thermal stability of nylon 6 by hexagonal boron nitride fillers

Abstract Mechanical and tribological properties of nylon 6 and nylon 6/h-BN composites were investigated in this paper. Tensile, hardness, and impact tests were carried out for mechanical properties, while wear tests on pin-on-disc were carried out for tribological properties identification. Abrasion resistance tests were carried out on the TABER apparatus to analyze the abrasive wear of materials. SEM, XRD, and TGA were used to characterize the materials and to understand the distinctive features of nylon 6 and nylon 6/h-BN composites. Experimental results show that the mechanical properties and tribological behavior of nylon 6 got enhanced by the h-BN fillers. Tensile strength and modulus of elasticity were enhanced by 15.2% and 64.5%, respectively, while hardness and impact strength were enhanced by 3.45% and 6%, respectively. COF and wear rate of composites decreased up to 4 wt% filler reinforcement due to smooth transfer film formation. Coefficient of friction (COF) and wear resistance were improved by 10–15% and 8–10%, respectively, at various testing conditions. h-BN reinforcement in the matrix resulted in more weight loss due to abrasion and it reduced the abrasion resistance of nylon 6 by 5.5 times. Thermal stability was slightly increased, and crystallinity was little affected by the h-BN fillers.

<i>In Situ</i> Reinforcement of PLA Using Nylon 6 in PLA/Nylon 6 Extrudate Blend via Twin-Screw Extrusion

This research was aimed to study the possibility of in-situ reinforcement of PLA by elongated Nylon 6 in PLA/Nylon 6 blend during elongating of PLA/Nylon extrusion. PLA was melt blending with Nylon 6 in a twin screw extruder with various compositions i.e. 5, 10, 15 and 20 % of Nylon 6. The extrudate was drawn after leaving extrusion orifice die of 3 mm in diameter, with the pulling speed of 12 cycles per minute. The extrudate gauge length 15 cm were used to perform tension test in order to investigate tensile properties. The blending between PLA and Nylon 6 with 11 phr of benzene sulfonamide (BSA), based on Nylon 6, as a plasticizer was also investigated at the same PLA/Nylon 6 blend ratios. The extrusion used conditions were also the same. Tension was also performed onto the extrudates with the gauge length 15 cm. Thermal degradation was also investigated. The SEM micrographs of blends in the longitudinal direction of PLA/Nylon 6 extrudate showed elongated of Nylon 6 in PLA matrix phase. The elongated of Nylon 6 phase in PLA matrix phase was found very clear in the plasticized blends. This phenomenon clearly occurred for the blends composition of both 95/5 and 90/10, with and without plasticizer. The results also showed that Young’s modulus of the blends with 5 % Nylon 6 was increased about 10 % whereas at 10 % nylon 6, the modulus was not significantly different from neat PLA. With the addition of plasticizer, nylon 6 was elongated more than that in the blend with un-plasticized Nylon 6. Due to the lack in interfacial adhesion, shown by SEM micrograph, tensile strength was found to be decreased. As expected, the elongation at break under tension was increased with the content of nylon 6. This was due to the toughening effect of elongated Nylon 6. Thermal stability, notified by degradation temperature of PLA, Td, was found to be improved. This was due to the high thermal stability of nylon 6. The results from the research can inform that the elongated nylon 6 phase in PLA matrix can perform as fibrous reinforcement. At high content of nylon 6, i.e. 15 and 20 %, the elongation of nylon 6 was rather difficult due to the less matrix phase and low shearing between PLA and nylon 6. Phase compatibility improvement could be the factor to improve the in-situ reinforcement.

<i>In Situ</i> Synthesis of Nylon 6/MgAl Layered Double Hydroxide (LDH) Nanocomposites by Hydrolyzed Ring Opening Polymerization

Nylon 6/MgAl-LDH nanocomposites had been successfully prepared by In situ hydrolyzed ring opening polymerization in this work. The structures and properties of Nylon 6/MgAl-LDH nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The nanodispersion of exfoliated MgAl-LDH layers in nylon 6 matrix has been verified by the observation of TEM image in Nylon 6/MgAl-LDH nanocomposites with 0.3 wt% MgAl-LDH (MANM-0.3). The XRD results showed that the exfoliated MgAl-LDH favored the formation of the γ-crystalline of nylon 6 form. DSC data showed that the exfoliated MgAl-LDH layers play the role of nucleating agents with strong heterogeneous nucleation effect on the crystallization of nylon 6. But TAG results showed the thermal stability of nylon 6/MgAl-LDH nanocomposites were worse than that of neat nylon 6.

Nonisothermal decomposition kinetics of nylon 1010/POSS composites

AbstractThe thermal stability of nylon 1010/polyhedral oligomeric silsesquioxane (POSS) composites prepared by melt blending was investigated with thermogravimetric analysis. The octavinyl POSS (vPOSS) and epoxycyclohexyl POSS (ePOSS) were used, and it was found that nylon/vPOSS composites have higher integral procedure decomposition temperature and char yield at 800°C than nylon/ePOSS composites. The Doyle–Ozawa (model‐free) and Friedman (model‐fitting) methods were used to characterize the nonisothermal decomposition kinetics of nylon 1010 and its composites. The activation energy (Ea), reaction order (n), and the natural logarithm of frequency factor of nylon 1010 were 267 kJ/mol, 1.0, and 47 min−1, respectively, in nitrogen. After the addition of POSS, the Ea of nylon 1010 considerably increased, whereas n had less change. The Ea steadily increased with increasing conversion and with increasing heating rate. The lifetime of nylon 1010 and its composites decreased with increasing temperature. At a given temperature, POSS significantly prolonged the lifetime of nylon 1010. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Radiation preparation of ultrafine carboxylated styrene-butadiene rubber powders and application for nylon 6 as an impact modifier

Ultrafine carboxylated styrene–butadiene rubber(CSBR) powders were prepared by using gamma irradiation and following spray-drying method. The influences of dose rate, absorbed dose, and sensitizer content on the crosslinking density of CSBR latices were studied in detail. Then the ultrafine CSBR powders were used to toughen nylon 6. The toughness and thermal properties of nylon 6/CSBR blends were measured by using notched lzod impact test and differential scanning calorimetry and thermogravimetry, respectively. Results showed that the crosslinking density of CSBR increased with increasing of dose and sensitizer content, and it is independent on dose rate. The notched Izod impact strength of nylon 6 under room temperature increased after incorporation of irradiation crosslinked CSBR powders with appropriate crosslinking density. The morphology of higher impact nylon 6/CSBR blends indicated that the finer dispersion existed with dispersed particles of 150-nm diameter. Fracture morphology of nylon 6/CSBR blend suggested that the shear yielding in matrix is the primary toughening mechanism for nylon 6/CSBR blends. The crystallinity of nylon 6/CSBR blends decreased slightly compared with pure nylon 6, whereas the addition of CSBR powders had little influence on the thermal stability of nylon 6. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3040–3046, 2002

Influence of acid dyes on the thermal behavior of nylon 66

To reveal the effect of acid dyes on the melt processing of recycled nylon 66, 17 acid dyes with different chemical structures were used to dye a nylon 66 yarn. The thermal stability of dyestuffs, the thermal degradation of the dyed nylon 66 during compression molding, and the melting and crystallization of the dyed nylon were investigated. During melt processing, most dyed nylon 66 changed color strength and color pattern. This is attributed to the migration and chemical reactions of dyestuffs. Acid dyes containing metal ions, such as C.I. Acid Black 60, C.I. Acid Red 186, C.I. Acid Yellow 151, and C.I. Acid Black 107, have severe impact on the thermal stability of nylon 66. The influence of metal complex acid dyes on the thermal stability of nylon 66 can be explained by a mechanism of acid-catalyzed nucleophilic acyl substitution. It was observed that the existence of acid dye in nylon 66 does not influence the melting temperature of nylon. However, some metal complex dyes reduce the crystallization temperature of molten nylon. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 371–382, 1998

Radiationresistance and thermal stability of nylon 6, acrylonitrile copolymer and polyester fabrics

AbstractThe thermal stability and radiation resistance of three polymers Nylon 6, acrylonitrile copolymer and polyester were investigated. The polymer samples were irradiated by low rate fission neutrons from a 252Cf source. The polyester showed a higher heat and radiation resistance than the two other polymers. It has to be recommended herein that polyester is the most suitable fiber for the manufacture of products in which heat buildup is produced during application, or products where radiation and heat resistance are required.

Thermal and dielectric properties of nylon 6

The thermal decomposition of nylon 6 has been studied between 25 and 550°C. Analysis of the data indicates that nylon 6 decomposes in a first-order reaction with a specific rate constant of 2.55–3.56 min −1 and an activation energy of 38.86–52.32 kcal mol −1 depending on the degree of crystallinity. The results indicate that the thermal stability of nylon 6 increases with the degree of crystallinity. The activation energy of relaxation, Δ H ϵ, calculated from dielectric loss measurements, was found to be 8.9 kcal and attributed to the polarization of the side groups of the polymer.